//起始时间
//1980年1月1日星期二
//前面有2个空位
//一年有365天  366天
//需要算出今年会365 还是366

var year=2019;
var month=5;
document.querySelector("#nian").innerHTML=year;
document.querySelector("#yue").innerHTML=month;
//总天数
var days=0;
//判断这一年是不是闰年
function runNian(y){
    if(y % 400 === 0||(y % 4 === 0 && y % 100 !==0)){
        return true;
    }else{
        return false;
    }
}
//算1980年到现在的头一年有多少天
for(var i=1980; i<year;i++){
    if(runNian(i)){
        days+=366;
    }else{
        days+=365;
    }

}
console.log(days);
//今年的1月到这个月的上一个月有多少天
//31
//28
//31
//30

for(var k=1;k<month;k++) {
    switch (k) {
        case 1:
            days += 31;
            break;
        case 2:
            if (runNian(year)) {
                days += 29;
            } else {
                days += 28;
            }
            break;
        case 3:
            days += 31;
            break;
        case 4:
            days += 30;
            break;
        case 5:
            days += 31;
            break;
        case 6:
            days += 30;
            break;
        case 7:
            days += 31;
            break;
        case 8:
            days += 31;
            break;
        case 9:
            days += 30;
            break;
        case 10:
            days += 31;
            break;
        case 11:
            days += 30;
            break;
        case 12:
            days += 31;

    }
}
    //算一下本月一共有多少天
    var day=0;
    switch(month){
        case 1:
            day+=31;
            break;
        case 2:
            if(runNian(year)){
                day+=29;

            }else{
                day+=28;
            }
            break;
        case 3:
            day+=31;
            break;
        case 4:
            day+=30;
            break;
        case 5:
            day+=31;
            break;
        case 6:
            day+=30;
            break;
        case 7:
            day+=31;
            break;
        case 8:
            day+=31;
            break;
        case 9:
            day+=30;
            break;
        case 10:
            day+=31;
            break;
        case 11:
            day+=30;
            break;
        case 12:
            day+=31;
            break;

    }
console.log(day);
    //算一下上个月一共有多少天
    var prevDay =0;
    if(month=1){
        prevDay+=31;
    }else{
        switch(month-1){
            case 1:
                prevDay+=31;
                break;
            case 2:
                if(runNian(year)){
                    prevDay+=29;

                }else{
                    prevDay+=28;
                }
                break;
            case 3:
                prevDay+=31;
                break;
            case 4:
                prevDay+=30;
                break;
            case 5:
                prevDay+=31;
                break;
            case 6:
                prevDay+=30;
                break;
            case 7:
                prevDay+=31;
                break;
            case 8:
                prevDay+=31;
                break;
            case 9:
                prevDay+=30;
                break;
            case 10:
                prevDay+=31;
                break;
            case 11:
                prevDay+=30;
                break;
            case 12:
                prevDay+=31;
                break;

        }
    }

console.log(prevDay);
//因为19800101是从星期二开始的，我想让它从星期热开始算，所以
days+=2;
console.log(days);
//算出本月的1号是星期几（算出其实位置）
var start=days%7;
console.log(start);

//算一下当前页面的日历一共可以放多少天
var num=42;
//前面空多少个
//本月有多少天？
//下一个月有多少天


var nextDays=num-start-day;

//取到今天是几号
var thisdate=new Date().getDate();
var date1=document.querySelector("#date1");
for(var j=prevDay-start+1;j<=prevDay;j++){
    date1.innerHTML+="<span class='h'>"+j+"</span>";

}
for(var a=1;a<=day;a++){
    if(a==thisdate){
        date1.innerHTML+="<span class='today'>"+a+"</span>";

    }else{
        date1.innerHTML+="<span>"+a+"</span>";
    }
}
for(var s=1;s<=nextDays;s++){
    date1.innerHTML+="<span class='h'>"+s+"</span>";
}